Sound-producing device



E. FRANTZ SOUND PRODUCING DEVICE March 30 1926'.

2` Sheets-Sheet l I I N ETOR. 44ML mi BY A i 2M fw www A TTORNEY.

Mar'ch 30 1926.

E. FRANTZ SOUND PRODUCIN': DEVICE Film1 F'e'b. s,

2 Sheets-Sheet 2 imitatie corr @Patented Mar. Y 30, 1926.

UNITED STATES PATENT OFFICE.

v SOUND-PRODUCING DEVICE.

Application led February 3, 1925. Serial No. 6,669.

To all 'whom it' may concer/ri.'

' Be it known that I, EMILE FiiAN'rz, citi` zen of the United States, residing at San Francisco, county of San Francisco, State of California, have invented new and useful Improvements in Sound-Producing Devices, ut which the following is a specification.

My invention has for its object means for securing an amplication of the sound from a telephone receiving mechanism, and is especially adapted to what is known as a loud speaking apparatus 'for radio and -telephone communication.

Other objects will ,appear from the drawing and specifications which `follow.

These objects I attain by a plurality of diaphragms operated in synchronism from a single armature which is positioned in a magnetic field, and which field is varied by electrical impulses corresponding with sound Wave vibrations which it is desired to transform and reproduce as sound at another point.

The vibration oi. the plurality of diaphragms establishes a sound wave through suitably arranged passageways.

Adjusting means are provided for varying the resiliency of the diaphragms jointly.

' Referring to the accompanying drawings.

Fig. 1 is a cross section through a loud speaking device employing my invention.

Fig. 2 is .similar to Fig-1 but showing a variation in the adjusting means and'of the sound amplifying passageways with certain of the parts left 'o ut.

Fig. 3 is a vsection of Fig. 1 on the line III-III with the sound vtubes removed.

Fig. 4 is a medial section through one of the diaphragme corresponding with a relatively loose adjustment.

Fig. 5 is similar to Fig. 4 but correspond? ingwith a relatively tight adjustment.

Fig. 6 is an enlarged cross Sectionl of conventional single diaphragm.

Fig. 7 is a diagram ot a pair of diaphragms, the sinn of whose thicknesses is equal to thethickness of the singlediaphragm, Fig'- 6.

Fig. 8 is a diagrammatic showing of a conventional sound vibration as produced by the diaphragms of Fig. 6 and Fig. 7.

Throughout the `figures similar numerals refer to identical parts.

The numerals 1, 2 indicate sections -of a vcoil surrounding the magnetic field 8 and 55 adaptedto be connected in any conventional telephone circuit. j

3 and 4 are the poles of the circular permanent magnet 5 having end pieces 6, 7 respectively, whereby a varying magnetic field is established in the space 8 which actuates the armature 9.

At 10 and 11 are a pair of diaphragms cminected together and to the armature 9 by the bar 12, whereby the diaphragms 10, 11 are .65 caused to vibrate in synclironism with the armature 9 and to reproduce the variations in the rmagnetic field 8 transmitted from the telephone circuit, which circuit is not shown but Well known, and in which the coil 1, 2 70 is connected.

The diaphragm 10 is mounted between supporting ring members 13, 14 and the diaphragm 11 between similar ring members 1.5, 16.

The rings are supported respectively between-'outside and inside plates 17, 18 and 19, 20. f

Between the plates 18 and 20 are a plurality ot supporting bars 21, in compression. Outside plates 22, 23 are held together by a plurality of tension members'24.

Plates 22, 23 are carried upon the tubes 25,

26 provided with external right and left threads with which the plates 22, 23 engage. 85 By rotating the plates 22, 23, on threaded tubes 25, 26, their corresponding end plates 17, 19 respectively will be compressed more orless against rings 13 and 16 establishing *,arelatively looser or tighter gripping of `the diaphragms -10 and 11 between the rings 3, Hand 15, 16, the purpose of which is more clearly set forth below.

From the. tubes 25, 26 conduits 27, 28 convey the sound impulses from the diaphragms 10, 11 respectively and these impulses may be brought together in the throat member 29 and amplified by the flaring tube 30.

In Fig. 2 the end plates are shown at 40,-

41 and an adjusting plate is shown at 43 carried on a threaded thimble member 44, mounted on the threads 42 of the sound tube 45.

The outer plates .tiand 4l are connected by a plurality of tension members 46 and a rotation ol' the single thiinbhl 44 varies the pressure between the diaphragm rings 13, 14 and l5, 1G held between the plates l8land by the compression members 21.

At 47 is shown a flaring i'orm of discharge throat and amplifying sound dispersion member 48.

Rings 13, 14 and 15, 1G are preferably Y ,made of resilient material and 1 have found phragm distortion' will correspond with the bending oi'l a beam fixed. at each end. The degree of bending or distortion will be greater in the case of Fig. 4 than in the Case of Fig, 6, for equal loading or impulse.

The diaphragm of. Fig. 5 will be more lhighly resilient and will respond with greater accuracy to high notes Whereas the diaphragm adjusted as shown in Fig. 4 will better respond to and reproduce low notes.

The intensity of the sound wave will be y proportional in any instanceto the ampli'- tutte of the diaphragm vibration, and the degree of the diaphragm distortion will be proportional to the variations et the magnetic eld and therefore to the electrical im- 4 pulse inthe coil l, 2.

It' a single diaphragm be employed, and the entire eii'ort of the armature be expended thereon and the amplitude of diaphragm movement or vibration will be indicated by the curve 50 of Fig. 8 and if the thickness of the said diaphragm correspend with the thickness or dimension 51 of Fig. G, then the amplitude of the vibration ot each of the diaphragms of Fig. 1 under an equivalent electric impulse and Where the thickness of said diaphragme is one halt ot the thickness 51 as indicated at 52, of Fig. 7 will have an amplitude of the vibration corresponding with the curve 54 of Fig. 8; in other words, with the same electrical impulse my pair of diaphragms will each vibrate with an amplitude twice as great as where a single diaphragm oi the same diameter and twice the thickness is employed. l

This is true, because the resistance to bending which must be overcome by the action of the magnetic field will vbe proportional to the square of the thickness of the diaphragm. My two diaphragme each being one-half the thickness of a single 4diaphragm will4 each offer a resistance one quarter that'of the thick diaphragm and the sum of these two will be one-halt that ofthe thick diaphragm.

`Wth auequivalent;impulsei will therefore attain twice the am' litude of vibration in each of the two dia-p iragms.

The amplitude of the diaphragm vibra tion determines the'lmagnitude oi the sound wat e, and as.cach"o-f..iny two diaphragms will, under agiven electric impulse, have twice the amplitude ot vibration the sound wave combined from the two will be very much greater than in the case of a single diaphragm, and except ior other losses as friction, eddy currents, ete.J the resulting sound impulse will be four times as great as with a single dial'ihragm.

The sound waves Yfrom the two diaphragms 10, 11 maybe combined in a singie throat piece 29 and amplified the tube 30, or the tube members 45, 47 may be einployed and leach anipliiied' through a separate dispersion element one of which is shown at 48 or anyconibination of ampiifying and dispersion device may be. en'ipioyed to suit the taste and requirements of any given case.

My invention is directed to the attainment of increased sound waves from a given magnetic field, and with my plurality oit da phragrns and adjusting means iter said diap hragms, any form ot magnetic field device or sound dispersion .means may be employed in combination therewith.

Also other means oi adjusting the sup-A porting rings of the diaphragme and other connecting means between the diaphragms may be employed without departin s from the spirit of my invention and I Wis i to be understood as claiming all such variations.

1. A sound' producing device comprising a trame and means supported thereby adapt ed to establish a magnetic field,'a circuit adapted tovary saidfiield, an armature within said field, a .plurality of diaphragme gripped in said frame and link meansvbe tween said diaphragms and said armature whereby said diaphragme are constrained to vibrate in synchronism with said armature in rsponse'to the variations of said field, resilient'rings :about the peripheries of said diaphragme. and screw actuated. means constructedk and adapted to variably con'ipress said rings against said diaphraoms and incljding an outsideI and inside p ate for each diaphragm and a plurality of conilll,

, pression struts between said inside pltes l and a plurality of tension members between said outside plates.

2. A sound producing device as set forth 5 in claim l'wherein said armature is posi-- tioned between said daphragms and asound tube embraces eu armature.

ch diaphragm oppositesaid 3. YA sound producing device as set forth i1 1 claim 1 wherein sand armature is pos1- 1 tloned between said diaphragme and a. sound tube embraces each diaphragml opposite said l armature and 'an amplifying throat member into which said tube dicharges.

EMILE FRANTZ. 

